First-Level Diagnostics (Do These First)

1. Verify account is active and in good standing (no suspension)
2. Check for network outages in customer's area (check outage map)
3. Confirm device is powered on and has battery charge
4. Verify airplane mode is OFF
5. Check that mobile data is enabled in settings
6. Restart device (power cycle)

Device Restart Procedure

• iPhone: Hold power + volume button, slide to power off, wait 30 seconds, power on
• Android: Hold power button, tap restart/reboot, wait for device to restart
• Wait 2-3 minutes after restart for network reconnection
• Test service after restart

Symptoms

• "No Service" or "No Signal" displayed
• Cannot make or receive calls
• No mobile data connection
• SOS or Emergency Calls Only shown

Troubleshooting Steps

1. Check for network outage in customer's area (use internal outage tool)
2. Verify SIM card is properly inserted and not damaged
3. Toggle airplane mode ON for 10 seconds, then OFF
4. Manually select network: Settings → Mobile Network → Network Operators → Select carrier manually
5. Remove and reinsert SIM card (power off device first)
6. Reset network settings (will clear WiFi passwords)
7. Test SIM in another device if available
8. If SIM works in other device: Device issue, refer to manufacturer
9. If SIM doesn't work in other device: SIM card replacement needed

Network Settings Reset

Symptoms

• Calls and SMS work but no internet
• Browser shows "No Internet Connection"
• Apps cannot load content
• Data icon (4G/5G/LTE) not showing

Troubleshooting Steps

1. Verify customer has remaining data allowance (check usage)
2. Check if data roaming is required (customer traveling abroad?)
3. Ensure mobile data is enabled: Settings → Mobile/Cellular → Mobile Data ON
4. Verify APN settings are correct (see APN configuration section)
5. Toggle mobile data OFF for 10 seconds, then ON
6. Switch airplane mode ON for 10 seconds, then OFF
7. Verify no data restrictions on specific apps (App Settings → Mobile Data)
8. Check if VPN is blocking connection
9. Reset network settings
10. If using 5G and having issues: Force 4G/LTE mode to test

APN Configuration

Symptoms

• Data works but very slow
• Videos buffer constantly
• Websites take long to load
• Apps timeout when loading

Troubleshooting Steps

1. Check customer's data usage - may be throttled after fair usage limit
2. Verify signal strength (need at least 2-3 bars for good speeds)
3. Check if customer in congested area (stadium, mall, event)
4. Ask customer to move to different location and test
5. Run speed test (recommend Fast.com or Speedtest.net)
6. Compare to expected speeds for their plan and location
7. Toggle airplane mode to force network reconnection
8. Switch between 5G/4G to test (Settings → Mobile Network → Preferred Network Type)
9. Clear app cache if specific app is slow
10. Check for device software updates

Expected Speed Ranges

Symptoms

• Choppy or robotic voice
• Echo or delay
• One-way audio (can hear them but they can't hear you)
• Calls dropping frequently
• Static or crackling noise

Troubleshooting Steps

1. Check signal strength during call (need minimum 2 bars)
2. Ask customer to move to different location with better signal
3. Test with different phone numbers to rule out far-end issue
4. Disable WiFi calling temporarily to test
5. Check if Bluetooth is connected (may be routing to car/headset)
6. Clean microphone and speaker openings
7. Test with wired headphones to isolate device issue
8. Remove phone case (may block microphone)
9. Restart device
10. Check for carrier settings update (iPhone)

Calls Dropping

1. Check customer's location - indoor coverage issues?
2. Verify no network congestion or outage
3. Check signal handoff issues (switching between towers)
4. Test in different location
5. Enable WiFi calling for indoor coverage
6. Check if VoLTE is enabled (better call quality and reliability)
7. Update device software
8. Reset network settings as last resort

Cannot Send or Receive SMS

1. Verify SMS service is not suspended (check account status)
2. Check message center number is configured (SMS Settings)
3. Verify recipient's number is correct (include country code if international)
4. Check if customer has blocked the sender (SMS Block List)
5. Clear messaging app cache and data
6. Try sending to different number
7. Toggle airplane mode
8. Restart device
9. Test with default messaging app (disable third-party app)

MMS Not Working

1. Verify mobile data is enabled (MMS requires data)
2. Check APN settings include MMS configuration
3. Ensure customer is not on WiFi only (turn on mobile data)
4. Verify MMS messaging is enabled in app settings
5. Check file size - images over 1MB may fail (recommend compression)
6. Clear messaging app cache
7. Reset APN to default
8. Test with default messaging app

SMS Message Center Numbers

WiFi Calling Not Working

1. Verify WiFi calling is enabled in device settings
2. Confirm feature is activated on account (may require subscription)
3. Check WiFi connection quality (need stable connection)
4. Register for WiFi calling (may need to enter emergency address)
5. Ensure WiFi router allows VoIP traffic (check firewall)
6. Restart device after enabling WiFi calling
7. Forget and reconnect to WiFi network
8. Update device software to latest version
9. Test with different WiFi network

WiFi Calling Setup

5G Not Showing / Not Connecting

1. Verify customer's plan includes 5G access
2. Confirm 5G coverage in customer's area (check coverage map)
3. Check device is 5G compatible
4. Ensure 5G is enabled: Settings → Mobile Network → Preferred Network Type → 5G or 5G Auto
5. Check if data saver mode is limiting 5G
6. Toggle airplane mode to force network reselection
7. Move to area with stronger 5G signal
8. Update device software and carrier settings
9. Reset network settings if needed

5G Connected But Slow

• May be on 5G NSA (non-standalone) - uses 4G core network
• Network congestion in area
• Fair usage policy may apply after data threshold
• Building interference (5G high-band has limited penetration)
• Recommend switching to 4G if 5G consistently slow

eSIM Activation Problems

1. Verify device is eSIM compatible
2. Ensure device is not carrier-locked
3. Check customer has stable WiFi or data connection for activation
4. Verify QR code is not damaged or obscured
5. Try manual entry using SM-DP+ address and activation code
6. Delete any pending eSIM profiles before adding new one
7. Restart device and try again
8. Check for device software updates
9. If all fails: Generate new eSIM QR code

eSIM Not Working After Activation

1. Verify eSIM is set as default line for calls/data
2. Check eSIM profile is enabled in settings
3. Toggle airplane mode
4. Reset network settings
5. Delete and re-add eSIM profile

Cannot Access Voicemail

1. Verify voicemail is set up (may need first-time setup)
2. Check voicemail number is correct: 121 (local) or +65xxxx121 (roaming)
3. Test calling voicemail directly instead of visual voicemail
4. Reset voicemail PIN if forgotten
5. Clear visual voicemail app cache
6. Restart device
7. Re-enable visual voicemail feature

Not Receiving Voicemail Notifications

1. Check notification settings for phone/voicemail app
2. Ensure Do Not Disturb is not enabled
3. Verify voicemail notifications are not blocked in system settings
4. Test with a voicemail to trigger notification
5. Clear voicemail app cache and data
6. Refresh visual voicemail

When to Escalate to Technical Support

• All basic troubleshooting steps completed without resolution
• Network outage affecting multiple customers in area
• SIM card replacement needed
• Account provisioning issues
• Suspected network equipment problem
• eSIM activation failures after multiple attempts
• Persistent issues after device restart and network reset

Information to Provide When Escalating

• Customer account number and mobile number
• Device make, model, and software version
• Specific issue description and symptoms
• All troubleshooting steps already completed
• Error messages (screenshots if available)
• When issue started (date/time)
• Customer's location (for coverage issues)
• Test results (speed test, call test, etc.)